X-ray unit with time delay means to prevent actuation thereof until explosive air is purged from the housing



Oct. 5, 1965 UNTIL EXPLOSIVE AIR IS PURGED FROM THE HOUSING Original Filed Aug. 17, 1959 Time Delay Switch Means Control On-Off Circuit Pressure Switch Line Confucior X-Ruy Tube Energizing Control High Voltage Transformer Fig.|.

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INVENTOR Frederick Eiioi WITN-ESjZ 3;

6W ii ATTORNEY United States Patent X-RAY UNIT WiTll-I TINiE DELAY MEAN TO PREVENT ACTUATIGN THEREOF UNTIL EX- PLOSIVE AIR IS PURGED FROM THE HGUSlNG Frederick Eliot, Linthicum, MdL, assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Continuation of application Ser. No. $34,129, Aug. 17, 1959. This application Mar. 12, 1963, Ser. No. 266,133

4 Claims. (Cl. 250-90) The present invention relates to X-ray apparatus and more particularly to a mobile X-ray unit which may be operated safely in such as an operating room in which anesthetics are employed.

The present application is a continuation of copending patent application Serial No. 834,129, filed August 17, 1959, now abandoned.

Up to recently, mobile X-ray units were low power, requiring long time exposures, because of this, they tended to be used mainly for treatment or examination of bed patients in .the rooms of a clinic or hospital where the patient could not be moved to the X-ray room. Currently, however, X-ray apparatus in mobile form is available with high power output, because of its flexibility and high power, new demands are being made of it. One of these demands is for its use in the operating room or rooms of the hospital. Here it is invaluable .for examination in connection with hip nailing, bone setting, etc. Such employment in the operating room of the hospital however, presents an element of danger.

The hospital operating room is an anesthetizing loca-. tion, and present day anesthetics such as cyclopropane, divinyl ether, ethyl chloride, ethyl ether or ethylene, can form (flammable or explosive mixtures when combined with air, sometimes resulting in serious damage. A prior technique for the use of X-ray equipment in such rooms has been to leave the X-ray machine including controls and high voltage supply for the X-ray tube in a nonhazardous location outside the anesthetizing room and to bring a special X-ray tube and cable into the operating room. Such technique requires relatively long cables and .the remote operation of the tube together with the relatively long cable attached thereto is rather cumbersome. Another technique has been to enclose the electrical apparatus associated with the tube in containers filled with inactive gas such as carbon dioxide or nitrogen, maintained under pressure from a bottled gas container. By employment of such technique, the entire unit including controls, etc, may be moved int-o the operating room without undue hazard. This latter technique, however, results in considerable increase in expense in equipment, due to initial sealing problems and subsequent servicing problems, and in undue heating of the components within the mobile unit, so that such unit may be employed only intermittently without causing undue excessive heating of the electrical components contained therein.

In view of the foregoing remarks, it becomes a prime object of the present invention to provide a mobile X-ray unit which may be employed with safety in a room in which anesthetics are used, and which is relatively free from the problems of sealing, servicing and overheating.

Other objects and advantages of the invention will become apparent from the following description thereof when taken in connection with the accompanying drawing in which:

FIG. 1 is a perspective view of the mobile X-ray unit embodying the invention; and,

FIG. 2 is a circuit diagram of safety control means embodied within the apparatus of FIG. 1.

Referring to FIG. 1 of the drawing, the mobile X-ray 312M547 Patented Get, 5, 1965 ice unit embodying the invention comprises the usual base 1 which is mounted on wheels 2 and which is provided with a housing 3 extending vertically from the base 1. The housing 3 comprises a lower portion 4 which may contain, for example, the usual high voltage transformer 5 disposed within a substantially oil-filled container 6.

Housing 3 also comprises an upper portion 7 in which may be contained, for example, the usual X-ray tube energization control means (not shown) such as the various relays, contactors, timing means, voltage regulators, etc., associated with X-ray equipment. The mobile unit also comprises a vertical column 8 on which is mounted a vertically-movable carriage means 9 having attached thereto an adjustably-mounted X-ray tube .10. A flexible, high voltage cable 11 serves to connect the X-ray tube 10 to the usual X-ray control apparatus disposed within the housing 13.

In accordance with the structural features of the invention, a motor-operated air blower 13 is provided at the top of the unit. The motor-operated blower 13 is ducted to the housing 3 at the top thereof for drawing air from the room at such location and forcing same downwardly through the housing 3 t-oexhaust restrictedly at the bottom thereof. Location of the blower 13 with respect to the base 1 and wheels 2 is such that same will be located above the floor level of the room in which the equipment may be used at a height above which the air is considered to be free of any potential for explosion during employment of anesthetics in such room. Currently, this level has been established to be five feet above the floor of such a room, Accordingly, the blower 13 and motor therefor as embodied in the mobile X-ray unit in accord with the present invention is located at a station above the housing 3 which is at least as high as five feet above the wheels 2 of such unit. The blower 13 is mounted within a housing .14 having ports, openings or louvers 15 at its front to admit air from above this five foot level to the inlet 16 of the blower means 13. In the embodiment shown in the drawing, the housing 14 is mounted on a hollow member 17 which serves as a duct connecting the outlet .18 of the blower .13 into the upper portion 7 of the housing 3. The bottom of the upper portion 7 of the housing 3 is open to the top of the high voltage transformer container 6 within the lower portion 4 of such housing by way of a conduit 19 and opening 19a in part-ition 28 between these .two portions. The top of transformer container 6 is provided with a restricted vent 21 for exhausting the air into the lower housing 4 which is provided with a plurality of vents 22 to provide for exit of air circulated downwardly by blower .13 through hollow member 17, upper housing 7, opening 19a, conduit 1-9, container 6, and restricted vent 21, into the lower housing member 4. The size of the restricted vent 2 1 with respect to the air handling capacity of the blower 13 is such as to provide some degree of restriction to the exhaus-t of air therethrough so that at all times the interior of the housing portion 7 and container 6 will be maintained at a pressure which is greater than the prevailing pressure of the atmosphere in the room surrounding the mobile unit.

From the foregoing, it will be apparent that by virtue of forcing air downwardly through the housing 3 of the mobile X-ray unit from above the level which is considered potentially hazardous in an operating room in which the unit may be employed, such safe air in surrounding the various electrical components associated with the X-ray tube energization and control circuit means within the respective containing portion of such housing 3 renders any sparks which may be associated with employment of such components harmless with respect to igniting or exploding any anesthetic-laden air which may surround the housing 3 at the potentially hazardous level below the aforementioned five foot level above the floor. Furthermore, it will be apparent that since the air output from the blower means 13 maintains the protected component enclosures within or part of the housing 3 at a pressure which is greater than the surrounding atmospheric pressure, none of such potentiallyexplosive atmospheric room air below such five foot level is able to enter such enclosures while the blower means 13 is in operation.

Referring to FIG. 2, in accord with additional features of the invention, safety circuit means are incorporated in the mobile unit to assure that the blower 13, during startup of equipment will first be brought into operation for a predetermined period of time and until a certain pressure has been created in housing portion 7 and transformer container 6 before the X-ray tube energization control means within the housing 3 is availed of supply line energy. To this end the mobile X-ray unit may be provided with a cable connector 30 located in association with housing 14 to accommodate connection of the usual 220 volt or -1 volt supply line to the blower motor 32 and to the equipment at a point which is more than five feet above the floor level to preclude the possibility of any sparks which may result from connection of the supply line to such connector 30 from igniting or exploding any of the potentially flammable air located below such level. The safety control means further includes a time delay switch means 31 which is mounted in the housing 14 and connected to one side of the line via the connector 30. Time delay switch means 31 is connected in series with a manually-operated control on-off circuit means 33 and normally-closed thermo switch means 34 in housing portion 7 and with a normally-open pressure switch means 35 in high voltage transformer container 6 to control connection of the line contactor 36 in housing 14 to the supply line via connector 30.

The line contactor 36 in turn controls connection of the X-ray tube energization control circuit 37 to the supply line connector 30.

In operation of the unit, the connector 30 will be coupled to a counterpart supply line connector (not shown), whereby the blower motor 32 is brought into operation to drive the blower 13 and cause same to draw explosion-safe air inwardly through louvers '15 in housing 14 and force such air downwardly through hollow member 17, into and through upper portion 7 of housing 3 containing the X-ray tube energizing control means 37, and, via opening 19a and conduit 19, downwardly into the top of the oil-filled container 6 housing the transformer 5, thence through the restricted vent 21 into the interior of lower housing portion 4 and into the room via vents 22.

Following a period of time suflicient to enable the thuscirculated explosion-safe air to purge housing 7 and transformer container 6 of any potentially-explosive air, and to build up positive air pressure within housing portion 7 and transformer container 6 adequate to prevent entrance thereinto of potentially-explosive air; the normally-open time delay switch means 31 and the normally-open pressure switch means 35 will close. The control system is then rendered effective, and the control on-off circuit means may be operated to establish connection of the X-ray tube energizing control means 37 to the supply line by closure of the line contactor 36 in response to establishment of its control circuit upon closure of switch means 31 and 35, thus it will be seen that any sparks which might result from operation of line contactor 36, control means 37, or of the control on-off circuit 33, in being surrounded by explosion-safe air circulated by the blower 13, will be prevented from causing an explosion or fire in a potentially hazardous locale in which anesthetizing agents are being employed. At the same time, the circulation of such air by the blower 13 over, around, and past the electrical circuit components Within the unit, will act to cool them and prevent their becoming over-heated. As an added safety measure, however, in event of any such undue heating, the thermo switch means 34 will respond to an air temperature within housing portion 7 in excess of F., for example, to open the control circuit to line contactor 36 for denergizing the X-ray tube energizing control means 37 and high voltage transformer 5 to protect such components as well as to preclude creation of a fire hazard in the presence even of safe air circulation,

If for any reason the positive air pressure within housing portion 7 and container 6 should drop below its desired value, the pressure switch means 35 will open to effect the desired opening of line contactor 36 and thus denergization of the equipment.

From the foregoing description, it will be apparent that, in accord with the invention, a mobile X-ray unit has been provided which affords safe operation in a hazardous location such as the operating room of a hospital in which anesthetics may be employed, that such unit affords such safety by means which is relatively simple and inexpensive, and, in addition to affording safe operation of the unit, the safety-providing means associated with such unit affords cooling of the electrical control means disposed within the housing of the mobile unit to assure prolonged operation of such unit without undue heating of such electrical components.

While the invention has been described herein with some degree of particularity, it will be apparent to those skilled in the art that certain changes in the preferred embodiment described herein may be made without departing from the spirit and scope of the invention as defined by the claims which follow:

I claim as my invention:

1. An explosion-safe mobile X-ray unit comprising a housing for location in an area in which the surrounding air may be potentially explosive, spark-producible electrical components disposed in said housing, said housing having air vents therein and an air inlet for admission of explosion-safe air into said housing for circulation therethrough to surround said spark-producible electrical components with such air, and safety interlock means including pressure responsive means and time delay means constructed and arranged to assure de-energization of said electrical components unless air pressure within said housing is greater than that at the exterior of the housing and until such relatively-positive internal air pressure has persisted for a period of time sufficient to purge said housing of any potentially explosive air.

2. An explosion-safe mobile X-ray unit comprising a vented housing for location in an area in which flammable anesthetics are employed, circuit means including sparkproducible components disposed in said housing within a vertical region corresponding to that in which the air in such area is considered to be potentially explosive during use of such anesthetics, said housing having an air inlet for admission of explosion-safe air into and through said vented housing to surround said spark-producible components with such air, and safety interlock means including time delay means and pressure responsive means constructed and arranged to prevent said circuit means being energized until after a certain positive pressure of circulated explosion-safe air admitted via said air inlet has been established in said housing for a period of time sufficient to purge such housing of any potentially-explosive air and prevent re-entrance of any of the latter during continued circulation of the explosion-safe air, while assuring rapid de-energization of said circuit means promptly upon subsequent reduction in the air pressure within said housing to less than said certain positive pressure.

3. An explosion-safe mobile X-ray unit comprising a vented housing for location in a room in which flammable anesthetics are employed, circuit means including sparkproducible heat-creatable components disposed in said housing within a vertical region corresponding to that in which the air within such a room is considered to be potentially explosive during use of such anesthetics, said housing having an air inlet for admission of explosion-safe air into and through said vented housing to surround said spark-producible components with such air, and safety interlock means including time delay means, pressure responsive means and temperature responsive means, constructed and arranged to prevent said circuit means being energized except during existence of a certain positive air pressure within said housing in persistence for a period of time suificient to purge said housing of any potentiallyexplosive air and except during existence of an air temperature within said housing below an unsafe value.

4. An explosion-safe mobile X-ray unit comprising a vented housing for location in a room in which flammable anesthetics are employed, electrical means including sparkprod-ucible and heat-creatable components disposed in said housing within a vertical region corresponding to that in Which the air within such a room is considered to be potentially explosive during use of such anesthetics, motoroperated blower means having an inlet at a vertical height on said unit efiective to draw air from an upper-vertical region of such room where the air is considered to be explosion safe during normal use of such anesthetics and displacing such air into and through said housing to surround said circuit means with such air, and safety interlock means including series-connected time-delay switch means, a pressure switch means and a thermo switch means constructed and arranged to assure de-energization of the aforesaid electrical means unless air pressure Within said housing is greater than air pressure at its exterior, when the temperature within said housing exceeds a safe limit, and until air pressure within said housing has been greater than that of the potentially-explosive housing-surrounding air for a period of time sufficient to assure purging of said housing of such housing-surrounding air.

References ited by the Examiner UNITED STATES PATENTS,

1,953,391 4/34 Bouwers 250-96 1,954,915 4/34 Bouwers 250- 2,022,644 12/35 Ashcraft 313-24 X 2,290,322 7/42 Goldfield 250-89 2,306,420 12/42 Allen 174-16 2,353,720 7/44 Goldfield et al. 250-89 2,542,016 2/51 Else et al. 310-88 2,756,368 7/56 Gross et al. 250-90 2,821,634 1/58 Myers et al 250-90 3,016,813 1/ 62 Frasier et al. 25-0-90 RALPH G. NILSON, Primary Examiner. 

1. AN EXPLOSION-SAFE MOBILE X-RAY UNIT COMPRISING A HOUSING FOR LOCATION IN AN AREA IN WHICH THE SURROUNDING AIR MAY BE POTENTIALLY EXPOLSIVE, SPARK-PRODUCIBLE ELECTRICAL COMPONENTS DISPOSED IN SAID HOUSING, SAID HOUSING HAVING AIR VENTS THEREIN AND AN AIR INLET FOR ADMISSION OF EXPLOSION-SAFE AIR INTO SAID HOUSING FOR CIRCULATION THERETHROUGH TO SURROUND SAID SPARK-PRODUCIBLE ELECTRICAL COMPONENTS WITH SUCH AIR, AND SAFETY-PRODUCIBLE ELECTRICAL COMING PRESSURE RESPONSIVE MEANS AND TIME DELAY MEANS CONSTRUCTED AND ARRANGED TO ASSURE DE-ENERGIZATION OF SAID ELECTRICAL COMPONENTS UNLESS AIR PRESSURE WITHIN SAID HOUSIING IS GREATER THAN THAT AT THE EXTERIOR OF THE HOUSING AND UNTIL SUCH RELATIVELY-POSITIVE INTERNAL AIR PRESSURE HAS PERSISTED FOR A PERIOD OF TIME SUFFICIENT TO PURGE SAID HOUSING OF ANY POTENTIALLY EXPLOSIVE AIR. 